guess controls in .oqp

.oqp control reference

Use canonical routes and controls in input files. Raw names identify implementation storage. A control without an accepted canonical spelling is not available in .oqp files.

The guess section controls initial orbitals, JSON restart files, and manual MO swaps. Most users can start with the default Huckel guess.

Minimal Example

rhf/6-31g*
geom="molecule.xyz"

Keywords

type

Canonical input call: guess(type=VALUE); VALUE is a placeholder for the documented value.

Field	Value
Type	string
Default	huckel
Values	huckel, modhuckel, hcore, json, auto, sap, minao
Used by	initial density/orbital construction

Selects the initial guess mode.

Value	Meaning
huckel	Native extended-Huckel style guess.
modhuckel	Modified Huckel guess.
hcore	Core-Hamiltonian guess.
json	Read orbitals and molecular data from a JSON restart file.
auto	Read file if it exists; otherwise fall back to Huckel.
sap	Superposition-of-atomic-potentials guess.
minao	Projected minimal-basis density guess.

Use json for exact restarts and auto for workflows that may or may not have a previous restart file.

file

Canonical input call: guess(file=VALUE); VALUE is a placeholder for the documented value.

Field	Value
Type	string
Default	empty
Used by	type=json, type=auto

Path to a JSON restart file. With type=json, the file must exist. With type=auto, OpenQP uses it when present and otherwise computes a fresh guess.

file2

Canonical input call: guess(file2=VALUE); VALUE is a placeholder for the documented value.

Field	Value
Type	string
Default	empty
Used by	NACME and previous-step workflows

Path to a second JSON restart file. NACME can use file2 for previous-step information. If it is omitted, NACME can instead use input.system2.

save_mol

Canonical input call: guess(save_mol=VALUE); VALUE is a placeholder for the documented value.

Field	Value
Type	boolean
Default	False
Used by	restart, orbital export, and inspection workflows

Requests saving molecular data for later restart or inspection. Supported bases also add portable AO basis, molecular-orbital, vibrational, and state-specific Dyson data for visualization. See Orbital and Vibrational Output.

continue_geom

Canonical input call: guess(continue_geom=VALUE); VALUE is a placeholder for the documented value.

Field	Value
Type	boolean
Default	False
Used by	JSON restart geometry

When true, reuses geometry from the JSON restart file. The input checker warns if continue_geom=true is set without type=json.

swapmo

Canonical input call: guess(swapmo=VALUE); VALUE is a placeholder for the documented value.

Field	Value
Type	comma-separated integer list
Default	empty
Used by	manual orbital reordering before SCF

Swaps molecular orbitals in pairs. The list must contain an even number of indices:

rhf/6-31g* guess(swapmo="2,7,8,21")
geom="molecule.xyz"

This swaps 2 with 7 and 8 with 21. Use it only when you know the target orbital ordering.

The swap acts on the alpha orbitals. What happens to the guess density depends on the guess type:

• Computed guesses (huckel, hcore, ...): the density of the computed guess is kept. The swap only names the occupation that rstctmo or mom then follow from the first iteration. Without one of them, the first Fock diagonalisation refills the lowest orbitals and the swap has no effect.
• Supplied guesses (json, auto with an existing file, previous): the guess density is rebuilt from the swapped orbitals, because a supplied guess can be accepted as converged on the first iteration and its orbitals and density must describe the same state. RHF: the doubly occupied density from the swapped orbitals. ROHF: both spin densities from the swapped alpha orbitals, and the beta orbitals are replaced by them. UHF: each spin density from its own orbitals.

Scientific references

HF and density functional theory; SCF convergence and response solvers.